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Old   November 28, 2002, 12:21
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Dear I am sorry disturb your mind . .. Today , i have thorny problem regarding writting the mass diffusion coefficient . Can you assist me to modify this program .. Because,i study this problem for a long times (about one to two years )...

In my model ,five species was be existed indie the model . H2,O2,H2O,CO2,N2

I don't want to choose a default setting from FLUENT's softward .

It isn't suited for my model .....must to write a new program of mass diffusion coefficient .

Dij=3.64e-8* T^2.334*(Pci*Pcj)^0.3333* (Tci*Tcj)^- 0.48625*(1/Mi+1/Mj)^0.5 /P

{ T ----cell temperature

P ----total pressure

Pci---critical pressure of species i

Pcj---critical pressure of species j

Tci---critical temperature of species i

Tcj---critical temperature of species j }

i want to solve the Dij from above equation . so. i also wrote a program of UDF by visual C++

Unfortunately , The software occurred a serious error message continuously to me ....The program is wrong in FLUENT . Who can assist to modify this thorny program ??


{ int i,j;

real Dij;

if(i==0. || j==1.)

{ C_DIFF_L(cell,thread,0,1)=3.64e-8*pow(C_T(cell,thread),2.334)/C_P(cell,thread)*pow((Pc0*Pc1),1/3)*pow((Tc0*Tc1),-0.48625)*((1/M0+1/M1),1/2); Dij=C_DIFF_L(cell,thread,0,1); }

else if(i==0. || j==2.) { C_DIFF_L(cell,thread,0,2)=3.64e-8*pow(C_T(cell,thread),2.334)/C_P(cell,thread)*pow((Pc0*Pc2),1/3)*pow((Tc0*Tc2),-0.48625)*((1/M0+1/M2),1/2); Dij= C_DIFF_L(cell,thread,0,2); }

else if(i==0. || j==3.)

{ C_DIFF_L(cell,thread,0,3)=3.64e-8*pow(C_T(cell,thread),2.334)/C_P(cell,thread)*pow((Pc0*Pc3),1/3)*pow((Tc0*Tc3),-0.48625)*((1/M0+1/M3),1/2); Dij=C_DIFF_L(cell,thread,0,3); } else if(i==0. || j==4.)

{ C_DIFF_L(cell,thread,0,4)=3.64e-8*pow(C_T(cell,thread),2.334)/C_P(cell,thread)*pow((Pc0*Pc4),1/3)*pow((Tc0*Tc4),-0.48625)*((1/M0+1/M4),1/2); Dij=C_DIFF_L(cell,thread,0,4); } else { C_DIFF_L(cell,thread,1,2)=3.64e-8*pow(C_T(cell,thread),2.334)/C_P(cell,thread)*pow((Pc1*Pc2),1/3)*pow((Tc1*Tc2),-0.48625)*((1/M1+1/M2),1/2); Dij=C_DIFF_L(cell,thread,1,2); }

return Dij; }

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